U.S. patent application number 11/224900 was filed with the patent office on 2007-03-15 for self-contained fork sensor having a wide effective beam.
This patent application is currently assigned to Banner Engineering Corporation. Invention is credited to Christopher Dales, Michael Dean, Charles Dolezalek.
Application Number | 20070057207 11/224900 |
Document ID | / |
Family ID | 37854159 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070057207 |
Kind Code |
A1 |
Dean; Michael ; et
al. |
March 15, 2007 |
Self-contained fork sensor having a wide effective beam
Abstract
A system and method for providing a fork sensor including an
emitter, a receiver, and at least one lens assembly wherein the
width of the effective beam does not depend upon the size of the
emitter or the receiver. One aspect of the present invention is a
method for detecting or counting the number of objects interrupting
the effective beam of the fork sensor. Another aspect of the
present invention is a method for measuring the dimensions of
objects using the fork sensor.
Inventors: |
Dean; Michael; (St. Paul,
MN) ; Dales; Christopher; (Minneapolis, MN) ;
Dolezalek; Charles; (Stacy, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Banner Engineering
Corporation
|
Family ID: |
37854159 |
Appl. No.: |
11/224900 |
Filed: |
September 13, 2005 |
Current U.S.
Class: |
250/559.12 ;
250/214R |
Current CPC
Class: |
G01V 8/10 20130101 |
Class at
Publication: |
250/559.12 ;
250/214.00R |
International
Class: |
H01J 40/14 20060101
H01J040/14; G01V 8/00 20060101 G01V008/00 |
Claims
1. A self-contained fork sensor comprising: an emitter for
generating a first beam of light; a first lens assembly coupled to
the emitter to receive the first beam of light having a first width
and to transmit a second beam of light having a second width, the
second width being greater than the first width; a second lens
assembly arranged and configured to receive the second beam of
light having the second width from the first lens assembly and to
transmit a third beam of light having a third width, wherein the
second width is greater than the third width; and a receiver to
receive the third beam of light from the second lens assembly for
generating an output signal.
2. The fork sensor of claim 1, further comprising: a signal
processor for receiving and processing the output signal generated
by the receiver.
3. The fork sensor of claim 1, further comprising a housing
including a first and second arm, the first arm containing the
first lens assembly and the second arm containing the second lens
assembly.
4. The fork sensor of claim 3, wherein the first lens assembly
further includes a dust shield.
5. The fork sensor of claim 3, wherein a distance between the first
and second arms ranges between 5 mm and 100 mm.
6. The fork sensor of claim 1, wherein the first lens assembly
includes a one-piece lens.
7. The fork sensor of claim 1, wherein the first lens assembly
includes a first lens and a redirecting feature.
8. The fork sensor of claim 1, wherein the beam emitted from the
first lens assembly is between 5 mm and 50 mm wide.
9. The fork sensor of claim 8, wherein the beam emitter from the
first lens assembly is 30 mm wide.
10. The fork sensor of claim 1, wherein the emitter is an LED.
11. The fork sensor of claim 1, wherein the receiver is a photo
diode.
12. A method for providing a wide effective beam in a
self-contained fork sensor, the method comprising: transmitting a
first electromagnetic (EM) beam to a lens assembly, the first EM
beam having a first width; modifying the first EM beam to create a
second EM beam substantially perpendicular to the first EM beam,
the second EM beam having a width substantially wider than the
first width; transmitting the second EM beam over a distance to the
lens assembly; and modifying the second EM beam to create a third
EM beam substantially perpendicular to the second EM beam, the
second EM beam having a width substantially wider than the third EM
beam.
13. The method of claim 12, wherein the lens assembly includes a
first and second lens assembly, wherein transmitting the first EM
beam to the lens assembly includes transmitting the first EM beam
to the first lens assembly, and wherein transmitting the second EM
beam to the lens assembly includes transmitting the second EM beam
to the second lens assembly.
14. The method of claim 12, wherein transmitting the second EM beam
over a distance to the lens assembly includes transmitting the
second EM beam to a reflective target and transmitting the second
EM beam from the reflective target back to the lens assembly.
15. The method of claim 12, further comprising receiving the third
EM beam at an EM receiver, wherein the EM receiver generates an
output signal based on the received EM beam.
16. The method of claim 12, further comprising: taking a base
reading of the output signal generated by the receiver;
interrupting at least a portion of the second EM beam by placing at
least one object between the first and second lens assembly; and
measuring changes in the output signal generated by the receiver
caused by an interruption of the second EM beam.
17. The method of claim 16, further comprising calibrating the
output signal of the receiver by measuring a change in the output
signal when a single object interrupts the second EM beam.
18. The method of claim 16, further comprising determining
dimensions of the object based on the changes in the output signal
of the receiver.
19. A self-contained fork sensor comprising: an emitter for
generating a first beam of light; a lens assembly including a first
surface and a second surface, the first surface configured to
receive the first beam of light from the emitter and to transmit a
final beam of light, the first and final beams having a first
width, the second surface configured to transmit a second beam of
light having a second width and to receive a third beam of light
having a third width, the third width being substantially greater
than the first width, the fourth width being substantially equal to
the third width; a target arranged and configured to receive the
second beam of light having the second width from the lens assembly
and to transmit the third beam of light having the third width to
the lens assembly; and a receiver for receiving the final beam of
light having the first width from the lens assembly, the receiver
generating an output signal based on the final beam.
20. The fork sensor of claim 19, further comprising a beam splitter
for transmitting the first beam of light from the emitter to the
lens assembly and for reflecting the final beam of light from the
lens assembly to the receiver.
21. The fork sensor of claim 19, wherein the lens assembly
includes: a first lens assembly for receiving the first beam of
light from the emitter and transmitting the second beam of light to
the target; and a second lens assembly for receiving the third beam
of light from the target and transmitting the final beam of light
to the receiver.
Description
TECHNICAL FIELD
[0001] The present invention relates to photoelectric sensors, and
more specifically to a self-contained photoelectric sensor having a
wide effective beam.
BACKGROUND
[0002] Photoelectric sensors debuted as throughbeam devices
composed of lights and reflectors. Over the years, these sensors
have developed into a multitude of designs, each used for a variety
of purposes. One of these designs is the self-contained
throughbeam, sometimes called a fork sensor. This sensor style,
typically configured in a block letter C-shape, sends an
electromagnetic signal (e.g., a beam of visible light, a laser
beam, etc.) across from one arm of the sensor to another.
Self-contained fork sensors can be used for a variety of
applications, such as in production lines. For example, the sensors
can be used to detect the presence or absence of items passing
through the beam along a conveyor.
[0003] FIG. 1 illustrates a schematic of a fork sensor 100
currently used in industry. Housing 110 of the fork sensor 100
includes a first and second arm 101, 102 extending from a base 105.
The first arm 101 includes an emitter 107 at a distal end 103. A
second arm 102 includes a receiver 108 at a distal end 104. The
emitter 107 is connected to a power source (not shown) and the
receiver 108 is connected to a signal processing assembly (not
shown). The emitter 107 is aligned with the receiver 108 such that
a beam of light transmitted by the emitter 107 is received by the
receiver 108 and converted into an electrical signal output.
Placing a sufficiently opaque object between the emitter 107 and
the receiver 108 interrupts a portion of the transmitted light
before it reaches the receiver 108, thereby changing the signal
output.
[0004] The beam of light has an effective width W.sub.1, which is
defined by the amount of light transmitted by the emitter 107 that
is also received by the receiver 108. The magnitude of the
effective width W.sub.1 depends on the size of the emitter 107 and
the receiver 108. Generally, both the emitter 107 and the receiver
108 are on the order of a couple millimeters wide. Therefore, the
effective width W.sub.1 of the beam is only on the order of a
couple millimeters.
[0005] In order for an object to interrupt the beam as it passes
between the emitter 107 and the receiver 108, at least a portion of
the object must pass within those few millimeters. Therefore,
movement of smaller objects through the fork sensor 100 must be
accurately controlled.
SUMMARY
[0006] In general terms, the present invention is a system and
method for providing a self-contained fork sensor having a wide
effective beam.
[0007] One aspect of the present invention includes a method for
providing a wide effective beam in a self-contained fork sensor.
The method includes transmitting a first electromagnetic (EM) beam
to a lens assembly, the first EM beam having a first width. The
method further includes modifying the first EM beam to create a
second EM beam substantially perpendicular to the first EM beam,
the second EM beam having a width substantially wider than the
first width. The method still further includes transmitting the
second EM beam over a distance to the lens assembly, and modifying
the second EM beam to create a third EM beam substantially
perpendicular to the second EM beam. The second EM beam has a width
substantially wider than the third EM beam.
[0008] In some embodiments, the lens assembly is a single lens
assembly. In these embodiments, transmitting the second EM beam
over a distance to the lens assembly includes transmitting the
second EM beam to a reflective target and transmitting the second
EM beam from the reflective target back to the lens assembly.
[0009] In some other embodiments, the lens assembly includes a
first and second lens assembly, and transmitting the first EM beam
to the lens assembly includes transmitting the first EM beam to the
first lens assembly. Transmitting the second EM beam to the lens
assembly includes transmitting the second EM beam to the second
lens assembly.
[0010] In one example embodiment, a self-contained fork sensor
includes an emitter, a lens assembly, a target, and a receiver. The
lens assembly includes a first surface and a second surface. The
first surface is configured to receive a first beam of light from
the emitter and to transmit a final beam of light to the receiver.
The second surface is configured to transmit a second beam of light
to the target and to receive a third beam of light from the target.
The second and third beams have widths substantially wider than the
first and final beams. The receiver receives the final beam of
light from the lens assembly and generates an output signal based
on the final beam.
[0011] In another example embodiment, a self-contained fork sensor
includes an emitter, a first lens assembly, a second lens assembly,
and a receiver. The emitter generates a first beam of light to the
first lens assembly. The first lens assembly receives the first
beam of light and transmits a second beam of light to the second
lens assembly. The second lens assembly receives the second beam of
light and transmits a third beam of light to the receiver. The
receiver receives the third beam of light and generates an output
signal. The second beam of light has a width substantially greater
than either the first or the third beam of light.
[0012] Embodiments of the present invention can be used to detect
the presence of objects, to count objects in gravity based
packaging, or to measure the dimensions of an object passing
anywhere along the length of the lens assemblies.
[0013] One aspect of the present invention is a method for counting
the number of objects passing between the effective beam of the
fork sensor. The method includes taking a base reading of an output
signal generated by the receiver. The method further includes
calibrating the fork sensor and measuring the changes in the output
signal resulting from objects interfering with the effective beam
of the fork sensor.
[0014] Yet another aspect of the present invention is a method for
measuring the dimensions of objects using a fork sensor. The method
includes taking a base reading and then placing an object within
the effective beam of the fork sensor so that the object blocks at
least a portion of the light beam. The method further includes
measuring the changes in the output signal generated by the
receiver based on the changes in the amount of the light reaching
the receiver.
[0015] In one embodiment of the present invention, a fork sensor
includes lens assemblies which are unitary in construction. In
another embodiment of the present invention, each lens assembly
includes a first lens and a redirecting feature.
DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a fork sensor as known in the art;
[0017] FIG. 2 illustrates a fork sensor according to one embodiment
of the present disclosure;
[0018] FIG. 3 illustrates a path and corresponding effective width
of a light beam as it propagates through a fork sensor assembly
according to one embodiment of the present disclosure;
[0019] FIG. 4 illustrates an alternative embodiment of a fork
sensor assembly;
[0020] FIG. 5 illustrates a single-piece lens for use in a fork
sensor according to one embodiment of the present invention;
[0021] FIG. 6 illustrates a portion of the single-piece lens of
FIG. 5;
[0022] FIG. 7 illustrates a lens structure for use in a fork sensor
according to another embodiment of the present invention;
[0023] FIG. 8a illustrates the transmission of a light beam between
a first lens assembly and a second lens assembly of a fork sensor
according to another embodiment of the present invention;
[0024] FIG. 8b illustrates the effect on the light beam
transmission of FIG. 8a when an object is placed between the first
and second lens assemblies;
[0025] FIG. 9 is a flow chart illustrating an example operational
flow for detecting objects using a wide beam fork sensor; and
[0026] FIG. 10 is a flow chart illustrating an example operational
flow for measuring the width of an object using a wide beam fork
sensor.
DETAILED DESCRIPTION
[0027] Various embodiments of the present invention will be
described in detail with reference to the drawings, wherein like
reference numerals represent like parts and assemblies throughout
the several views. Reference to various embodiments does not limit
the scope of the invention, which is limited only by the scope of
the claims attached hereto. Additionally, any examples set forth in
this specification are not intended to be limiting and merely set
forth some of the many possible embodiments for the claimed
invention.
[0028] Referring now to FIGS. 2-4, a wide beam fork sensor includes
a light emitter, a light receiver, and at least one lens assembly
extending substantially the length of one arm of the fork sensor.
One end of each lens assembly is configured to transmit or receive
a first beam having an effective beam width extending substantially
along the length of the lens assembly. Another end of each lens
assembly is configured to transmit or receive a second beam having
an effective beam width extending substantially less than the
effective beam width of the first beam.
[0029] Referring now to FIG. 2, in some embodiments, the light
emitter and light receiver are oriented towards a first lens
assembly extending along a first arm of the fork sensor and a
second lens assembly extending along a second arm of the fork
sensor, respectively. FIG. 2 illustrates a fork sensor 200
including a housing 220 having a first and second arm 221, 222
extending from a base 225. In some embodiments, the first and
second arms 221, 222 extend intermediate 5 mm and 50 mm. However,
the length of the first and second arms 221, 222 is limited only by
the dimensions of the desired overall fork sensor 200. In some
embodiments, the first and second arms 221, 222 are spaced
intermediate 5 mm and 100 mm apart. However, the distance
intermediate the first and second arms 221, 222 is also limited
only by the dimensions of the desired overall fork sensor 200.
[0030] The base 225 includes an emitter 207 at one end 213 and a
receiver 208 at another end 214. However, the embodiment is not
limited by the location of the emitter 207 and receiver 208 and
these components can be located in other areas of the fork sensor
200 without deviating from the spirit of the present
disclosure.
[0031] In one embodiment, the emitter 207 is positioned and
oriented to emit an EM (e.g., light) beam along the length of the
first lens assembly 201. The frequency of the transmitted light is
limited only by the ability of the receiver 208 to accurately sense
the light. According to one embodiment, the emitter 207 is an LED
that emits visible light. According to another embodiment, the
emitter 207 emits infrared light. According to yet another
embodiment, the emitter 207 generates ultraviolet light.
[0032] The receiver 208 is positioned and oriented to receive the
transmitted light. In one embodiment, the receiver is a
semiconductor photodiode. However, the embodiment is not limited to
a photodiode and any suitable photosensor can be used.
[0033] In one embodiment, a power source 209 is also included
within the base 225. The emitter 207 is electrically connected to
the power source 209. According to another embodiment, the power
source 209 is external to the housing 220 and is electrically
connected to a power supply line (not shown) leading into the
housing 220. In this embodiment, the power supply line is
electrically coupled to the emitter 207. Examples of power sources
include batteries, voltage generators, solar cells and the
like.
[0034] In one embodiment, a signal processing assembly 211 is
included within the base 225. According to this embodiment, the
receiver 208 is electrically connected to the signal processing
assembly 211. In another embodiment, the signal processing assembly
211 is external to the housing 220 and is electrically connected to
a signal transmission line (not shown) leading out of the housing
220. In this embodiment, the signal transmission line is connected
to the receiver 208.
[0035] In one embodiment, a first and second attachment hole 215,
216 are defined by the base 225. These holes 215, 216 enable the
fork sensor 200 to be attached to a surface using fasteners such as
screws, nails, pegs, or the like. However, the embodiment is not
limited to these fasteners and any suitable fastener can be used,
such as a bonding material or the like.
[0036] According to one embodiment of the fork sensor 200, the
first arm 221 includes a first lens assembly 201 and the second arm
222 includes a second lens assembly 202. When power is supplied to
the emitter 207 from the power source 209, the emitter 207 emits a
photon beam towards the first lens assembly 201. The first lens
assembly 201 is arranged and configured to direct (e.g., or
reflect, or refract) the light beam towards the second lens
assembly 202. The second lens assembly 202 is arranged and
configured to receive and focus the light beam onto the receiver
208. The receiver 208 transforms the received light beam into an
electrical signal, which is then output to the signal processing
assembly 211. The path followed by the light beam will be explained
in more detail herein with respect to FIG. 3.
[0037] Still referring to FIG. 2, each lens assembly 201, 202
includes a first surface 203, 204 extending substantially along the
length of the respective arms 221, 222. Each lens assembly 201, 202
further includes a second surface 205, 206 extending along the
width of the respective arms 221, 222. The first lens surface 203,
204 of each lens assembly 201, 202 is substantially perpendicular
to the respective second lens surface 205, 206. The first lens
assembly 201 is configured so that light received at the second
lens surface 205 of the first lens assembly 201 will be directed
through the first lens surface 203 of the lens assembly 201 towards
the second lens assembly 202. Example lens surface 203, 205
configurations include a flat surface and a curved surface. The
second lens assembly 202 is configured so that light received at
the first lens surface 204 will be directed through the second lens
surface 206 and towards the receiver 208. Example lens surface 204,
206 configurations include a flat surface and a curved surface.
[0038] Each arm 221, 222 of the fork sensor 200 provides an open
section, or window, 231, 232, respectively, through which the light
propagating between the two arms 221, 222 enters and exits the
housing 220. Each opening 231, 232 extends substantially along the
length of the respective arm 221, 222. According to one embodiment,
the openings 231, 232 include a slit provided by the housing 220.
According to another embodiment, the openings 231, 232 include a
piece of glass, plastic, or other such transparent material
allowing light to pass through relatively unaffected. The open
sections 231, 232 are generally defined by the planar lens surface
203, 204. However, the embodiment is not limited to the above
dimensions and any suitable dimension can be used.
[0039] FIG. 3 illustrates a schematic depicting a sensor assembly
according to one embodiment of the present disclosure. The sensor
assembly 300 includes a first lens assembly 310 and a second lens
assembly 320. The first lens assembly 310, which is depicted in
dashed lines, includes a first lens 302 and a second lens 303. The
second lens assembly 320, which is also depicted in dashed lines,
includes a first lens 304 and a second lens 305. The sensor
assembly 300 further includes an emitter 307 oriented towards the
first lens 302 of the first lens assembly 310 and a receiver 308
oriented towards the second lens 305 of the second lens assembly
320.
[0040] The emitter 307 transmits a beam of light along a path B in
the direction of the first lens assembly 310. The beam of light has
a width W.sub.2 upon leaving the emitter 307. The beam enters the
first lens assembly 310 at the first lens 302. The beam has a beam
width W.sub.3 when it reaches the first lens 302. In one
embodiment, the beam of light diverges before it reaches the first
lens 302 of the first lens assembly 310. In this case,
W.sub.3>W.sub.2. In another embodiment, the beam of light does
not diverge while traveling towards the first lens 302. In this
case, W.sub.3=W.sub.2. In yet another embodiment, the beam
converges as it travels towards the first lens assembly 310 such
that W.sub.3<W.sub.2.
[0041] The light beam propagates through the first lens assembly
310 until it reaches the second lens 303. The beam exits from the
second lens 303 of the first lens assembly 310 and is transmitted
along a path C towards the second lens assembly 320. The path C
extends between the first and second lens assemblies 310, 320.
Generally, the length of the second lens 303 of the first lens
assembly 310 defines the width W.sub.4 of the transmitted light
beam along a path C such that W.sub.4>W.sub.2. In one possible
embodiment, path C has a width W.sub.4 of 33 millimeters. However,
the invention is not limited to this width and any suitable width
can be used.
[0042] Upon reaching the second lens assembly 320, the light beam
passes through the first lens 304 and is directed towards the
second lens 305. The light beam has a width W.sub.5 as it passes
through the second lens 305 and travels along a path D to the
receiver 308. Generally, the width W.sub.5 of the beam exiting the
second lens assembly 320 is less than the width W.sub.4 of the beam
entering the assembly 320. Finally, the light beam is received at
the receiver 308, which has a width W.sub.6. The width W.sub.6 of
the receiver is generally less than the width W.sub.4 of the path C
between the first and second light assemblies 310, 320. In one
embodiment, the width W.sub.6 of the receiver 308 is on the same
order as the width W.sub.2 of the emitter 307. However, the
invention is not limited to this width relationship and the
receiver 308 can be any suitable width.
[0043] Referring now to FIG. 4, in some other embodiments, a fork
sensor includes only one arm. FIG. 4 illustrates a retro-reflective
fork sensor 400 including a housing 420 having an arm 421 extending
from a base 425. The base 425 includes an emitter 407 having a
width W.sub.2 and a receiver 408 having a width W.sub.6. The arm
421 includes at least one lens assembly 410. Each lens assembly 410
is arranged and configured to transmit light to a target 430, the
light having an effective width W.sub.4, which is substantially
wider than the widths W.sub.2, W.sub.6 of the emitter and receiver
407, 408.
[0044] In some embodiments, the target 430 is external of the fork
sensor housing 420. In other embodiments, the target 430 is
contained within a second arm (e.g., as shown in FIG. 2, element
222) of the fork sensor housing 420. The target 430 is arranged and
configured to reflect a substantial portion of the light received
from the lens assembly 410 back to the lens assembly 410. Various
example embodiments of the target 430 are formed from reflective
prisms and spheres.
[0045] In some embodiments, the arm 421 includes only one lens
assembly 410. The emitter 407 is oriented to transmit light to the
lens assembly 410 and the receiver is oriented to receive light
from the lens assembly 410. In these embodiments, the base 425
further includes a beam splitter 435 arranged and configured to
transmit light received from the emitter 407 to the lens assembly
410, but to reflect light received from the lens assembly 410 to
the receiver 408.
[0046] In some other embodiments, the arm 421 includes a first and
second lens assembly 410a, 410b, respectively. The first and second
lens assemblies 410a, 410b are arranged and configured to transmit
and receive light without interfering with one another. In one
example embodiment, the first lens assembly 410a is positioned on
top of the second lens assembly 410b. In some embodiments, the base
425 includes an emitter 407 positioned and oriented to transmit
light to the first lens assembly 410a and a receiver 408 positioned
and oriented to receive light from the second lens assembly 410b. A
beam of light travels from the emitter 408 to the first lens
assembly 410a, which transmits the light to the target 430. The
target 430 reflects the light to the second lens assembly 410b,
which transmits the light to the receiver 408.
[0047] Similar to the fork sensor depicted in FIG. 2, some
embodiments of the base 425 of the fork sensor 400 include a power
source and a signal processing assembly (not shown). In other
embodiments, the base 425 includes power supply lines and signal
transmission lines (not shown). Generally, any suitable means may
be used to power the emitter 407 or to analyze a signal generated
by the receiver 408 without deviating from the spirit and scope of
this disclosure.
[0048] FIGS. 5-7 illustrate different possible embodiments of the
lens assemblies 310, 410. FIG. 5 illustrates one possible
embodiment of a lens assembly 310, 410 that includes a single-piece
lens 500. An emitter 550 emits a beam of light towards a
single-piece lens 500. The single-piece lens 500 includes a first
surface 501 through which light from the emitter 550 enters the
single-piece lens 500, a second surface 502 through which the light
exits the single-piece lens 500, and a third surface 503 for
receiving the light from the first surface 501 and transmitting the
light to the second surface 502. The first surface 501, the second
surface 502, and the third surface 503 are all formed from a single
piece of material. Generally, the first surface 501 is oriented
substantially perpendicular to the second surface 502. However, the
invention is not limited to this orientation and any suitable
orientation may be used.
[0049] The first surface 501 is arranged and configured so that
light generated by the emitter 550 will propagate in a generally
straight line after passing through it. In one embodiment, the
first surface 501 is convexly shaped to focus a diverging beam of
light into a non-diverging beam. In another embodiment, the first
surface 501 is flat, enabling a non-diverging beam of light to pass
through unaltered. In yet another embodiment, the first surface 501
is concavely shaped to refract a converging beam of light into a
straight, non-converging beam. Generally, the width SW.sub.1 of the
first surface 501 ranges between one and twenty millimeters.
Typically, the width SW.sub.1 of the first surface 501 is 10
millimeters. However, the embodiment is not limited to these
dimensions and any suitable dimensions can be used.
[0050] The second surface 502 is arranged so that light 541 exiting
through the surface 502 is shaped substantially like beam spot 540.
Beam spot 440 illustrates one pattern of light; however, the
invention is not limited to the pattern formed by beam spot 540,
and any suitable pattern may be used, such as square, oval or the
like. Generally, the height H.sub.1 of the second surface 502
ranges from 1 mm to 5 mm as illustrated in the beam spot 540. In
one embodiment, the width SW.sub.2 of the second surface 502 is
much greater than the width SW.sub.1 of the first surface 501. In
another embodiment, the width SW.sub.2 of the second surface 502 is
about the same as the width SW.sub.1 of the first surface 501.
Generally, the width SW.sub.2 of the second surface 502 ranges
between 10 and 50 millimeters. Typically, the width SW.sub.2 of the
second surface 502 is 33 millimeters.
[0051] The third surface 503 of the single-piece lens 500 is
arranged to reflect light from the first surface 501 to the second
surface 502. Generally, the width SW.sub.3 of the third surface 503
ranges between 15 and 50 millimeters. Typically, the width SW.sub.3
of the third surface is about 38 millimeters. However, the
embodiment is not limited to these dimensions, and any suitable
dimensions can be used. Generally, an area is formed by the first
surface 501, second surface 502, and third surface 503, in which
the second and third surfaces 502, 503 are defined by an angle O.
Typically, the angle O between the second surface 502 and the third
surface 503 ranges between 5.degree. and 45.degree.. In one
possible embodiment, the angle O is about 15.degree.. However, the
embodiment is not limited to these dimensions and any suitable
dimensions can be used.
[0052] According to one embodiment, the single-piece lens 500 is
formed from an acrylic material. One example of such a material is
Polymethyl methacrylate (PMMA). According to another embodiment,
the single-piece lens 500 is formed from glass. According to yet
another embodiment, the single-piece lens 500 is formed from
plastic, fiberglass, plexi-glass, or the like. However, the
invention is not limited to these materials and any suitable
material can be used.
[0053] FIG. 6 illustrates one embodiment of a portion 600 of the
third surface 503 of the single-piece lens 500 as illustrated in
FIG. 5. The portion 600 of the reflective surface 503 includes a
series of undulations (e.g., ridges) 605. The undulations 605 are
arranged and configured to reflect a beam of light entering through
the first surface 501 out towards the second surface 502. The
undulations 605 are further arranged and configured to reflect
towards the second surface 502 a beam of light having a larger
width than the beam propagating from the first surface 501.
[0054] These undulations 605 are composed of a first surface 606
and second surface 607. In one embodiment, the first surface 606
and second surface 607 are flat and oriented generally
perpendicular from each other. In another embodiment, the first and
second flat surfaces 606, 607, are angled obliquely from each
other. In yet another embodiment, the undulations 605 are composed
of a series of Gaussian shaped waves (not shown) having first and
second halves 606, 607. In still yet another embodiment, the
undulations 605 are composed of first and second curved surfaces
(not shown) angled either orthogonally or obliquely from one
another.
[0055] In one embodiment, light rays entering through the first
surface 501 propagate through the single-piece lens 500 and reach
the first surface 606. Surface 606 is arranged and configured to
reflect the light rays towards the second surface 607 of the
undulation 605. Surface 607 is arranged and configured to reflect
the light waves towards the second surface 502. Generally, each
undulation surface 606, 607 ranges between 0.1 millimeter and 0.7
millimeter. Typically, each undulation 605 extends over a length of
0.25 millimeter. However, the invention is not limited to
undulations of this size and any suitable undulation size may be
used.
[0056] FIG. 7 illustrates one possible embodiment of a lens
assembly 310, 410 that includes a lens structure 700. An emitter
750 emits a beam of light towards the lens structure 700. The lens
structure 700 includes a first lens 705 and a redirecting feature
710. Light generated by the emitter 750 propagates to the first
lens 705, which directs the light towards the path modification
feature 710. The redirecting feature 710 bends (e.g., or redirects)
the light so that it propagates in a non-diverging, wide beam along
a direction F towards either a target (as illustrated in FIG. 4,
element 430) or a second lens assembly (as illustrated in FIG. 3,
element 320).
[0057] According to one embodiment, the first lens 705 is arranged
and configured to modify (e.g., refract) diverging light from the
emitter 750 into a non-diverging beam 713. According to another
embodiment, the first lens 705 is arranged to modify converging
light into a non-diverging beam. In yet another embodiment, the
first lens 705 is arranged and configured to enable a non-diverging
light beam to pass unaltered. In one embodiment, the first lens 705
is not connected to the redirecting feature 710. In another
embodiment, the first lens 705 is connected to the redirecting
feature 710.
[0058] In some embodiments, the redirecting feature 710 includes a
series of peaks (e.g., ridges) 712. Each peak 712 has an angled
surface 714 oriented towards the first lens 705. In one embodiment,
the first lens 705 is angled obliquely in relation to the
redirecting feature 710. Light rays passing through the first lens
705 are directed towards the angled surface 714 of each peak 712.
Upon reaching the angled surface 714, the light rays are refracted
along a path in the direction F to form a beam 716 of light having
a width W.sub.6. The angled surface 714 is arranged so that light
716 is shaped substantially like beam spot 740. Beam spot 740
illustrates one pattern of light; however, the invention is not
limited to the pattern formed by beam spot 740, and any suitable
pattern may be used, such as square, oval or the like.
[0059] In one embodiment, the redirecting feature 710 further
includes a dust shield 715 for keeping dust and other such
particles off of the redirecting feature 710. Interference from
dust or other such particles on the surface of the redirecting
feature 710 can cause the light to bend at an undesired angle,
which would cause the resulting beam to diverge or converge rather
than propagate in a straight line. According to one embodiment, the
dust shield 715 is spaced from the redirecting feature 710, but is
still contained within the housing of the fork sensor (see, e.g.,
FIG. 2, element 220 and FIG. 4, element 420). According to another
embodiment, the housing of the fork sensor defines the dust shield
715.
[0060] Referring now to FIGS. 8-10, some example applications for a
wide beam fork sensor are illustrated. FIGS. 8a and 8b illustrate
embodiments of fork sensors 800a, 800b utilizing a wide effective
beam to detect, count, and measure objects 850. FIG. 8a illustrates
an unobstructed light beam traveling between a first lens assembly
805 and a second lens assembly 810 of the fork sensor 800a. In
other embodiments, the fork sensors 800a, 800b are configured
similar to fork sensor 400 depicted in FIG. 4 and have only one
lens assembly 805. The lens assemblies 805, 810 have a beam width
of Q. FIG. 8b illustrates the effect on the light beam when an
object 850 having a width O, such that Q.gtoreq.O, is placed
between the first and second lens assemblies 805, 810.
[0061] Referring now to FIG. 9, embodiments of the fork sensor 800
are used in various industrial processes. In some embodiments, the
fork sensor 800 is utilized to detect objects in a gravity-fed
packaging process. In other embodiments, the fork sensor 800 is
utilized to detect small parts ejected from a manufacturing process
such as a metal stamping machine. In still some other embodiments,
the fork sensor 800 is utilized to verify an assembly process such
as sensing a cap on a small bottle. FIG. 9 illustrates a flow chart
depicting an operation flow 900 for detecting objects 850 using a
wide beam fork sensor 800. The process 900 will be described with
reference to FIGS. 8a and 8b.
[0062] The process starts at module 905 and proceeds to setup
operation 910. Setup operation 910 includes providing a fork sensor
800 having a first and second wide lens assembly 805, 810, an
emitter 815, and a receiver 820. Power is supplied to the emitter
815 in powering operations 915. Supplying power causes the emitter
815 to transmit a beam of light in the direction of the first lens
assembly 805. The beam of light is then transmitted from the first
lens assembly 805 to the second lens assembly 810, which transmits
the beam to the receiver 820. The receiver 820 is arranged to
receive the beam and to convert the beam into an electrical signal
output.
[0063] In a sensor calibration operation 920, a first reading
measuring the signal output from the receiver 820 is taken. The
first reading represents the amount of light received when the
light from the emitter 815 reaches the receiver 820 without
interruption or diversion. Module 925 changes the flow of
operations 900 based on whether objects 850 are being counted or
merely detected. If objects 850 are being counted, then the sensor
800 is further calibrated in object calibrating operation 927. This
operation will be discussed in greater detail herein. If objects
850 are merely being detected, then the process proceeds directly
to sensing operation 930.
[0064] Sensing operation 930 includes dropping one or more objects
850 through the beam propagating between the first and second lens
assemblies 805, 810 of the fork sensor 800. The objects pass
through the beam extending between the first and second lens
assemblies 805, 810. When one of the objects is located in the path
of the beam, at least some of the light from the beam is blocked
from reaching the second lens assembly 810. Blocking at least a
portion of the light causes the signal output of the receiver 820
to decrease. This decrease is detected in processing operation 935.
The process 900 ends at module 940.
[0065] If the process 900 had proceeded to object calibrating
operation 927, then the fork sensor 800 would have been further
calibrated to measure the change in signal output from the receiver
820 due to a single object 850 passing through the beam of light.
This operation assumes that objects 850 of generally the same
dimension will be passing through the beam at generally the same
velocity. Once object calibrating operation 927 is completed, then
the process proceeds to sensing operation 930. The quantity of
object 850 passing through the beam can then be determined using
methods known in the art in processing operation 935 from the
information gathered in sensing operation 930.
[0066] Pills being packaged using a gravity-fed packaging process,
machine parts being transported by a conveyer belt, and small parts
being ejected from a manufacturing process, are examples of objects
850 that can be detected and counted. However, the invention is not
limited to the detection of these objects, and any object capable
of breaking the beam, or a portion thereof, can be detected.
[0067] Referring now to FIG. 10, embodiments of the fork sensor 800
can also be used to measure various objects 850. In one example
embodiment, the fork sensor 800 measures the diameter of an
extruded tube. In another example embodiment, the fork sensor 800
guides an edge of a web-based process, using analog or discrete
outputs. FIG. 10 illustrates a flow chart depicting an operational
flow 1000 for measuring objects 850 using a fork sensor 800 having
a wide effective beam. The process 1000 will be discussed with
reference to FIGS. 8a and 8b.
[0068] The process starts at module 1005 and proceeds to setup
operation 1010. A fork sensor 800 having a first and second lens
assembly 805, 810, an emitter 815, and a receiver 820 is provided
in setup operation 1010. The emitter 815 is arranged to transmit a
beam of light when supplied with power. The receiver 820 is
arranged to receive the beam of light and to convert the beam into
an electrical signal output. The first and second lens assemblies
805, 810 extend along a substantial portion of the fork sensor 800.
At this stage, the area between the first and second lens
assemblies 805, 810 is not obstructed by any objects 850.
[0069] Power is supplied to the emitter 815 in powering operation
1015. The power causes the emitter 815 to emit a beam of light 811
in the direction of the first lens assembly 805, which transmits
the light towards the second lens assembly 810 such that the beam
passing between the assemblies 805, 810 has a width Q. The second
lens assembly 810 transmits the light 813 towards the receiver 820.
Calibrating operation 1020 includes taking a first reading of the
received signal output from the receiver 820. The first reading
represents the signal received when the beam of light passes
between the two lens assemblies 805, 810 without interruption or
divergence.
[0070] An object 850 having a width O is placed in the path of the
light beam between the two lens assemblies 805, 810 in placement
operation 1025. Because the width Q of the light beam is greater
than the width O of the object, only a portion of the light is
blocked from reaching the second lens assembly 810. In sensing
operation 1030, a second reading is taken of the received signal
output from the receiver 820. The difference between the first
signal output and the second signal output is calculated in
processing operation 1035. This difference can be mathematically
converted into a dimensional measurement using methods known in the
art. The process 1000 ends at module 1040.
[0071] The various embodiments described above are provided by way
of illustration only and should not be construed to limit the
invention. Those skilled in the art will readily recognize various
modifications and changes that may be made to the present invention
without following the example embodiments and applications
illustrated and described herein, and without departing from the
true spirit and scope of the present invention, which is set forth
in the following claims.
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